Strand-guiding roller

ABSTRACT

A strand-guiding roll for supporting and guiding cast metal strands in a continuous casting installation, having a central rotatable shaft and having at least one roll shell supported fixed against rotation on this shaft. To enable the strand-guiding roll to cope with the mechanical and thermal stresses, the roll shell is supported by support rings or by a support-ring sleeve on the shaft. An annular space, which is axially delimited by the support rings for the shell, is formed between the shaft and the roll shell. The annular space is a coolant conduit.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a 35 U.S.C. 371 national phase conversion ofPCT/EP2004/003770, filed 8 Apr. 2004, which claims priority of GermanApplication No. A 615/2003, filed 23 Apr. 2003. The PCT InternationalApplication was published in the German language.

BACKGROUND OF THE INVENTION

The invention relates to a strand-guiding roll for supporting andguiding cast metal strands in a continuous casting installation, havinga central rotatable shaft and having at least one roll shell supportedfixed against rotation on this shaft.

Strand-guiding rolls are used in continuous casting installations tosupport and guide continuously cast metal strands after they emerge froma mold in a strand-guiding stand. They are exposed to high thermalstresses, since the cast metal strands leave the mold at a temperatureof over 1000° C. if they are steel strands for example. In the case ofrelatively thick strands, there is still a pronounced liquid core in thestrand, as a result of which ferrostatic forces act on thestrand-guiding rolls. In addition, the strand-guiding rolls have towithstand deformation forces from the strand bending. Accordingly, thestrand-guiding rolls are usually equipped with internal cooling and areof a robust design suitable for the mechanical stresses. Theconsiderable width of the cast strands requires multiple mounting of thestrand-guiding roll and accordingly a multi-part structure.

In conventional continuous casting installations, two basic types ofstrand-guiding rolls, which differ in terms of their basic structure,are used.

One basic type of strand-guiding rolls comprises a stationary centralaxle, on which one or more roll shells are rotatably supported by way ofsliding or rolling bearing arrangements. Strand-guiding rolls of thistype are already known, for example, from DE-A 197 44 077, DE-A 27 45578, DE-A 38 23 655 and U.S. Pat. No. 4,351,383. On account of therelative movement between individual components of the strand-guidingrolls, it is necessary to provide bearing arrangements which are exposedto thermal stresses and accordingly require protective measures.

A further basic type of strand-guiding rolls avoids the need for bearingarrangements of this type within the rolls and comprises a centralrotatable shaft and roll shells mounted fixedly in terms of rotationthereon. An outline representation of a strand-guiding roll of this typeis to be found in DE-A 29 35 217.

DE-A 25 52 969 has disclosed a further strand-guiding roll with amultiply mounted continuous shaft, on which individual roll sections arearranged fixed in terms of rotation by a welded joint. An annular spaceas coolant conduit is formed between the central shaft and the rollsections and is connected to central supply lines. This welded designmeans that the strand-guiding roll cannot be dismantled, and thereforethe roll sections, which are subjected to high thermal and mechanicalstresses, cannot be replaced.

WO 93/19874 has disclosed a strand-guiding roll, the roll bodies ofwhich are formed substantially as a single piece. However, it is verycomplex and expensive to produce the coolant lines passing through theroll body.

WO 02/38972 A1, based on FIGS. 1a and 1b, reports a prior art whichinvolves a strand-guiding roll with a central, multiply mounted shaftand a plurality of roll shells arranged thereon. The entire innersurface of each roll shell bears against the outer surface of the shaft,and is connected to it fixed against rotation by way of a feather key.This strand-guiding roll is internally cooled via a coolant line whichruns centrally within the shaft. A strand-guiding roll of this type hasthe fundamental drawback of a long heat-transfer path from the shellsurface to the coolant line. Gaps between the shaft and the roll shellact as an insulator and additionally impede the dissipation of heat fromthe strand-guiding roll.

Furthermore WO 02/38972 A1 has disclosed a strand-guiding roll with amultiply mounted shaft and roll shells fitted onto it, each roll shellbeing arranged fixed against rotation on the shaft by means of a featherkey. An annular space, which is filled with a material with a highthermal conductivity, is provided between the roll shell and the shaftover part of the longitudinal extent of the roll shell. The dissipationof heat from the strand-guiding roll is effected by internal cooling viaa central coolant line which passes through the shaft. Although thethermally conductive filler avoids the barrier action of an air gapbetween the roll shell and the shaft, the considerable distance betweenthe thermally stressed roll shell surface and the coolant linenevertheless still exists.

Therefore, it is an object of the present invention to avoid thedrawbacks of the known prior art and to propose a strand-guiding rollwhich is able to better cope with the mechanical and thermal stresseswhich occur as a result of the strand. In particular, the way in whichthe roll shell is supported on the shaft is to be able to better matchthe stresses which occur.

SUMMARY OF THE INVENTION

In a strand-guiding roll of the type according to the invention, thisobject is achieved by virtue of the fact that the roll shell issupported via support rings on the shaft, that an annular space which isaxially delimited by the support rings is formed between the shaft andthe roll shell, and the annular space is designed as a coolant conduit.

Forming the support rings as independent components and arranging themin the edge regions of each roll shell means that forces are introducedinto the shaft in the region close to the supporting roll bearings. Peakthermal and mechanical loads caused by deformation and wear are avoided.At the same time, corresponding steps in the shaft diameter at thecontact surfaces with the support rings allow simple assembly anddismantling of the strand-guiding roll for maintenance work and forreplacing a roll shell.

Forming an annular space, which is axially delimited by the supportrings, between the shaft and the roll shell creates regions which areseparate from one another, on the one hand for dissipating forces and onthe other hand for dissipating heat from the roll shell, and precludesdisruptive interaction.

To avoid leaks at the annular space, sealing elements, preferablysealing rings inserted in annular grooves, are arranged between thesupport rings and the roll shell and between the support rings and thecentral shaft.

The annular space is designed as a coolant conduit, which is connectedto a coolant line arranged in the central shaft via radial branch linesfor supplying and discharging a coolant. The radial branch lines openout within the longitudinal extent of the support rings into an annulargroove in the support ring which is open toward the annular space via amultiplicity of outlet openings.

An advantageous configuration consists in providing a plurality ofradial branch lines distributed over the cross section of the shaft,both in a coolant feed plane and in a coolant discharge plane, so thatan axial flow of coolant which is as uniform as possible is achievedover the entire circumference of the annular space. In addition,diverting devices, which make the axial flow profile in the annularspace even more uniform, may be installed in the annular space.Accordingly, the radial branch lines open out within the longitudinalextent of the support rings into an annular groove in the support ringwhich is open toward the annular space via a multiplicity of outletopenings.

The roll shell is secured against rotation with respect to the shaft bya rotation-preventing means, preferably a feather key, and therotation-preventing means in this case passes through the annular space.Arranging the rotation-preventing means within the annular space betweenthe two support rings means that the flow conditions for the coolant arescarcely impaired. However, sealing problems, which arise if therotation-preventing means is arranged at a supporting surface of theroll shell on the shaft, as is the case in the strand-guiding rolldescribed in WO 02/38972 A1, are avoided.

According to a further possible embodiment of the strand-guiding rollaccording to the invention, two support rings, which support a rollshell on the shaft, are connected to form a support-ring sleeve, and anannular space, the axial extent of which is delimited by the supportrings, is formed between the roll shell and the support-ring sleeve.Sealing elements and coolant conduits are designed analogously to theembodiment described above. The rotation-preventing means passes throughthe annular space and the support-ring sleeve.

One possible configuration of the passage of coolant through thestrand-guiding roll consists in the fact that the coolant line whichruns within the central shaft starts from one end side of the centralshaft, and the coolant line for discharging coolant arranged in thecentral shaft opens out at the opposite end side of the central shaft,and each coolant line is assigned a rotary connection piece.

One advantageous embodiment, which allows the supply of coolant to thestrand-guiding rolls to be restricted to one side of the installation orside of the strand guidance, consists in the fact that the coolant lineswhich run within the central shaft open out in one end side of thecentral shaft, and these coolant lines are assigned a multiple rotaryconnection piece. This embodiment can be used for both driven andundriven strand-guiding rolls.

The coolant used is usually cooling water.

Further features and advantages of the present invention will emergefrom the following description of a non-restricting exemplaryembodiment, in which reference is made to the appended figures, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through a strand-guiding rollaccording to the invention,

FIG. 2 shows a cross section through the strand-guiding roll on line A-Ain FIG. 1,

FIG. 3 shows a further embodiment of the strand-guiding roll accordingto the invention in longitudinal section through a roll section.

The illustrations in the figures show a strand-guiding roll according tothe invention in the form of a diagrammatic illustration, as issuitable, for example, for use in a strand-guiding section of acontinuous casting installation for producing metal strands of aconsiderable width, with a slab or thin slab cross section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The strand-guiding roll illustrated in FIG. 1 comprises a central shaft1, which is supported rotatably in four bearings 2. The bearings and thebearing housings which support them are in turn supported in astrand-guiding stand (not shown) of a continuous casting installation.

The bearings used are usually rolling-contact bearings. The centralshaft 1 is assigned three roll shells 3, each of the three roll shellsbeing supported on the shaft 1 by way of, in each case, two supportrings 4. The bearings 2 are located outside the longitudinal extent ofthe adjacent roll shells 3. A rotation-preventing means 5 rotationallyfixes the position of each roll shell 3 with respect to the shaft 1. Anannular space 6, which forms a coolant conduit, is provided between thesupport rings 4 of a roll shell 3, the inner lateral surface of the rollshell and the outer lateral surface of the shaft 1. Strand-guiding rollsof the type according to the invention have at least two, and usuallythree, roll shells.

The strand-guiding roll is equipped with internal cooling. The passageof the flow of coolant is indicated by arrows in FIG. 1. The coolantsupply takes place on one end side of the strand-guiding roll via arotary connection piece 10, and the discharge of coolant takes place atthe opposite end side of the strand-guiding roll via a rotary connectionpiece 11. The coolant is introduced into the annular space 6 through acentral coolant line 12, radial branch lines 13 which branch off from itand an annular groove 14 in the support ring 4 with axially orientedoutlet openings 19. The coolant, distributed over the entire crosssection of the annular space 6, flows through the annular space 6parallel to the longitudinal axis 15 of the strand-guiding roll and iscollected again in an annular groove 16 in the support ring 4 anddischarged through radial branch lines 17 into the central coolant line18. The coolant line 18 either leads to further branch lines 13 of afurther roll shell 3 or, after it has passed through all the roll shells3, to the discharging rotary connection piece 11, through which thecoolant leaves the strand-guiding roll again. To ensure that no coolantemerges from the annular space, a sealing element 20 is fitted betweenthe support ring 4 and the roll shell 3 and a sealing element 21 isfitted between the roll shell 3 and the shaft 1. The sealing elementsare formed by sealing rings inserted into annular grooves.

However, the supply of coolant and the discharge of coolant through thecentral coolant lines may also take place on just one side, i.e. one endside of the central shaft, via a double rotary connection piece, withthe result that the provision of coolant is restricted to one side ofthe strand-guiding arrangement and therefore one side of a continuouscasting installation.

In the case of a driven strand-guiding roll, the central coolant linesfor the supply and discharge of coolant, starting from one end side ofthe strand-guiding roll, are inevitably guided parallel to thelongitudinal axis of the shaft, since the roll drive is assigned to theopposite end side. Accordingly, the attached rotary connection piece isequipped with two coolant connections.

FIG. 2 shows, in the form of a cross section of the shaft 1 on sectionline A-A in FIG. 1, an end view of the support ring 4 illustrating thepassage of coolant in this region. The coolant is introduced from thecentral coolant line 12 via the branch lines 13 into an encirclingannular groove 14 in the support ring 4, where it is distributed andpassed through a multiplicity of outlet openings 19 which aredistributed over the circumference and may be designed as grooves orbores, to the annular space 6 between roll shell 3 and shaft 1,illustrated in FIG. 1. The reverse sequence is produced when the coolantis being discharged from the annular space 6.

This type of coolant routing allows heat to be dissipated from the rollshell as uniformly and efficiently as possible with little manufacturingtechnology.

The rotation-preventing means 5 for securing the position of the rollshell 3 on the shaft 1 is formed by one or more feather keys 23, whichpass through the annular space 6 and are arranged between two supportrings 4 which support a roll shell 3. In the region of the annular space6 there is sufficient space for a long feather key 23, so thatcircumferential forces or torques which act on the roll shell can besupported with little surface pressure on the shaft, in particular inthe case of driven strand-guiding rolls.

A further embodiment of the strand-guiding roll according to theinvention is illustrated in FIG. 3 in the form of a longitudinal sectionthrough part of the strand-guiding roll, in which identical referencedesignations are used for identical or equivalent components.

The roll shell 3 is supported via support rings 4 on the central shaft1, with the two support rings 4 arranged at the edge regions of the rollshell being connected by a sleeve 25 to form a support-ring sleeve 26.The support-ring sleeve 26 has a longitudinally extending opening 27,through which the rotation-preventing means 5 passes. Thisrotation-preventing means 5 secures the position of the roll shell 3with respect to the central shaft 1. An annular space 6, which forms acoolant conduit, is provided between the support rings 4 of asupport-ring sleeve 26 assigned to a roll shell 3, the inner lateralsurface of the roll shell 3 and the outer lateral surface of thesupport-ring sleeve 26.

The strand-guiding roll is equipped with internal cooling. The flow ofcoolant is indicated by arrows in FIG. 3. The coolant is supplied on oneend side of the strand-guiding roll via a rotary connection piece 10 andthe coolant is discharged at the opposite end side (not shown) of thestrand-guiding roll through a further rotary connection piece. Thecoolant is passed through a central coolant line 12, radial branch lines13 which branch off from the central coolant line 12 and an annulargroove 14 in the support ring 4 with axially oriented outlet openings 19into a further annular groove 28 and, from there, is introduced throughfurther radial branch lines 29, which pass through the support-ringsleeve 26 in the radial direction, into the annular space 6. Thecoolant, distributed over the entire cross section of the annular space6, flows parallel to the longitudinal axis 15 of the strand-guiding rollthrough the annular space 6 and is passed, via radial branch lines 30which pass radially through the support-ring sleeve 26, into an annulargroove 31 and is collected again in an annular groove 16 of the supportring 4 and discharged through radial branch lines 17 into the centralcoolant line 18. The coolant line 18 leads either to further branchlines of a further roll shell or, after the coolant has passed throughall the roll shells, to the discharging rotary connection piece, throughwhich the coolant leaves the strand-guiding roll again.

1. A strand-guiding roll for supporting and guiding cast metal strandsin a continuous casting installation, the roll comprising: a centralrotatable shaft; at least one roll shell supported on and fixed againstrotation on the shaft; support rings on the shaft supporting the rollshell; the shaft, the roll shell and the support rings being shaped todefine an annular space which is axially delimited by the support ringsand is formed between the shaft and the roll shell; and connections tothe annular space for the space to be a coolant conduit via theconnections, the connections to the annular space comprising a coolantline arranged in and extending along a direction of an axis of thecentral shaft and radial branch lines from the coolant line, the coolantand branch lines being operable for supplying a coolant to anddischarging the coolant from the annular space, wherein the supportrings have respective annular grooves, the radial branch lines open outwithin a longitudinal extent of the support rings and into the annulargrooves in the support rings, and the annular grooves in the supportrings open toward the annular space, a multiplicity of outlet openingsopening the annular grooves toward the space.
 2. A strand-guiding rollfor supporting and guiding cast metal strands in a continuous castinginstallation, the roll comprising: a central rotatable shaft; at leastone roll shell supported on and fixed against rotation on the shaft;support rings on the shaft supporting the roll shell; the shaft, theroll shell and the support rings being shaped to define an annular spacewhich is axially delimited by the support rings and is formed betweenthe shaft and the roll shell; and connections to the annular space forthe space to be a coolant conduit via the connections, wherein two ofthe support rings support the at least one roll shell on the shaft, thetwo support rings are connected to form a support-ring sleeve, and theannular space has an axial extent which is delimited by the supportrings, the annular space being formed between the roll shell and thesupport-ring sleeve.
 3. The strand-guiding roll as claimed in claim 2,further comprising sealing elements arranged between the support ringsconnected by the support-ring sleeve and the roll shell and between thesupport rings and the central shaft.
 4. The strand-guiding roll asclaimed in claim 3, wherein the support rings have respective annulargrooves, and the sealing elements comprise sealing rings inserted in theannular grooves in the roll shell.
 5. The strand-guiding roll as claimedin claim 2, further comprising the connections to the annular spacecomprising a coolant line arranged in and extending along a direction ofan axis of the central shaft and radial branch lines from the coolantline, the coolant and branch lines being operable for supplying acoolant to and discharging the coolant from the annular space.
 6. Thestrand-guiding roll as claimed in claim 2, further comprising arotation-preventing device passing through the annular space and shapedto secure the roll shell against rotation with respect to the shaft. 7.A strand-guiding roll for supporting and guiding cast metal strands in acontinuous casting installation, the roll comprising: a centralrotatable shaft; at least one roll shell supported on and fixed againstrotation on the shaft; support rings on the shaft supporting the rollshell; the shaft, the roll shell and the support rings being shaped todefine an annular space which is axially delimited by the support ringsand is formed between the shaft and the roll shell; connections to theannular space for the space to be a coolant conduit via the connections;and sealing elements arranged between the support rings and the rollshell and between the support rings and the central shaft, wherein thesupport rings have respective annular grooves, and the sealing elementscomprise sealing rings inserted in the annular grooves in the rollshell.